1. Field of the Invention
The present invention relates to portable devices such as IC cards and, more particularly, to a contact type portable device which is connected to through connection terminals, and a non-contact type portable device which has a battery built therein as a power supply.
2. Description of the Related Art
Generally, a contact type IC card has a microcomputer for IC cards which is mounted in the card, and transfers data to and from an external terminal through connection terminals extending from the microcomputer to the card surface. In practice, the IC card is set in a reader/writer (not shown) and data is transferred to and from an external system under this condition.
FIG. 16 is a functional block diagram of a conventional contact type IC card 1. The IC card 1 has five connection terminals, i.e., V.sub.DD, GND, RST, CLK and I/O terminals. Data is serially transferred through the I/O terminals. Serial data input through the I/O terminal is subject to serial/parallel conversion in a UART 6, and then taken into a CPU 2 through a bus 7. The CPU 2 processes the data in accordance with the processing program loaded in a masked ROM 3 beforehand, loads the data, which is required to be stored temporarily, in a RAM 4, and loads the data such as processing results, which is required to be stored for a long period of time, in an EEPROM 5 as a data memory. The data which is output is subject to parallel/serial conversion in the UART 6, and then transferred to the exterior through the I/O terminal in series.
The start-up operation of the IC card 1 will now be described. When the IC card 1 is set in the reader/writer, V.sub.DD and GND voltages are first supplied from the reader/writer to the IC card through the V.sub.DD and GND terminals, respectively. Then, a reset signal is input from the reader/writer to an internal reset signal generator 8 in the IC card 1 through the RST terminal. As shown in FIG. 17, the reset signal is inverted by an inverter 8a of the internal reset signal generator 8, latched by a latch 8b and then supplied as an internal reset signal RSTZ to the other circuits in the IC card 1. These circuits in the IC card 1 are thereby brought into reset states. Under this condition, a clock signal is started and supplied from the reader/writer through the CLK terminal. Then, after inverting the reset signal to release the reset states, usual data transfer and data processing are executed.
Next, a non-contact type IC card will be described with reference to FIG. 18. Unlike the contact type IC card 1 of FIG. 16, a non-contact type IC card 11 has no terminals for connection to an external terminal on its surface, and transfers data in a non-contact manner using radio waves or the like. The non-contact type IC card 11 executes data processing in a non-contact manner when a card user brings the card into the vicinity of a system device. A battery 20 as a power supply is built in the non-contact type IC card 11, and an oscillator 15 is started up with electric power supplied from the battery 20 for supplying a clock signal to all other parts in the card. When data is received by the card, an analog signal received through an antenna 19 is converted by a modulator/demodulator 18 into a digital signal which is delivered to an input/output controller 16. The digital signal delivered to the input/-output controller 16 is read by a CPU 12 through a bus. 17 and is processed in accordance with the processing program loaded in a masked ROM 13 beforehand. The data which is required to be stored is loaded into a RAM 14 by the CPU 12. On the other hand, when data is transmitted from the card, the data to be output is delivered to the modulator/demodulator 18 through the input/output controller 16 for conversion into an analog signal. The analog signal is then transmitted out of the card through the antenna 19.
In the conventional contact-type IC card 1, the input sequence of the reset signal is important because it is essential that the reset signal be supplied through the RST terminal upon application of the source power, and the card may malfunction if the reset signal is not surely input. Another problem in terms of integrity is that if the operation from application of the source power to supply of the reset signal and the clock signal does not progress as per the sequence when the card user sets the contact-type IC card 1 in the reader/writer, or if the terminals connected to the reader/writer have any connection failure, the data stored in the RAM 4 and the EEPROM 5 in the IC card 1 may be damaged.
Also, in the conventional contact-type IC card 1, the supply sequence of the reset signal upon application of the source power is important to ensure reliability of the IC card 1 because the IC card 1 is used for a variety of readers/writers and the reset signal is supplied from each of these readers/writers through the RST terminal. In other words, the IC card 1 must be always surely brought into a reset state before starting operation. Up to now, however, the supply sequence of the reset signal depends on reliability of the reader/writer, and the IC card 1 has no ability to deal with troubles in the resetting.
Meanwhile, in the conventional non-contact type IC card 11, particularly in a non-contact type IC card 11 which is mass-produced at the present, it is customary that the card is entirely enclosed to increase security and ensure water resistance, etc. and hence the built-in battery 20 cannot be replaced with new one. This means that the service life of the battery 20 incorporated in the card determines the service life of the card itself. In the non-contact type IC card whose price is much higher than that of magnetic stripe cards in widespread use at the present, therefore, it is desired to keep consumption of the battery 20 as small as possible and to prolong the service life of the card. Also, because of the battery 20 is enclosed, the oscillator 15 in the card continues oscillating and the battery 20 continues consuming the electric power stored therein after the battery has been mounted during the manufacture step. There is a considerable period of time from the manufacture of the non-contact type IC card 11 to actual use thereof by the card user in many cases, raising a problem of shortening the effective period in which the card can be used.